Genetic studies on Saxifraga rosacea

Full title: Consequences of ploidy level on the reproductive isolation, ecological niche differentiation and plasticity of two subspecies of Saxifraga rosacea.

Abstract

Despite technological advances at the molecular level, it is still difficult to differentiate two subspecies of closely related taxa. It is often necessary to combine genetic techniques with ecological studies to distinguish each of them. The main purpose of the present project is to assess the importance of ecological niche differentiation that can be found between two closely related species with different ploidy levels. We will cross by artificial pollination, two subspecies of Saxifraga rosacea: Saxifraga rosacea subsp. rosacea (hexaploid) and Saxifraga rosacea subsp. sponhemica (tetraploid), and measure the offspring performance and establish whether the differences in ploidy levels create a reproductive isolation. We will also test the ecological isolation of both subspecies by measuring various environmental habitat characteristics like temperature or humidity. These measures will help to determine the optimal environmental conditions for the establishment and survival of the two subspecies. We will also study their demography, with measures at different life stages of the two sub-species to determine their life cycle. Finally we want to test the plasticity and adaptation of Saxifraga rosacea subsp. rosacea and Saxifraga rosacea subsp. sponhemica using climate chambers with controlled conditions in temperature and/or hygrometry. A common garden experiment will be conducted at the MNHNL with both subspecies in order to study the plasticity and robustness to environmental treatments such as hydric stress and competition by other species. The expected results will enable us to complete the results of a current PhD project of the museum, which focuses on the phylogenetic and phylogeographic aspects of the two subspecies and to allow a better understanding of particular links between speciation, plasticity and adaptation. Our results will also have implications for the conservation and management of these taxa. Saxifraga rosacea subsp. sponhemica is an endangered species of special conservation interest as a large number of the known extant populations occur in Luxembourg.

Status of PhD

Supervisor at university: Prof. Dr. Matthies Diethart, Phillips-University Marburg, Germany.

Supervisor in Luxembourg: Dr. Colling Guy, Population biology research group, National Museum for Natural History, Luxembourg.

PhD granted by Fonds national de la recherche Luxembourg. Duration: 3 years (01.03.2012 – 28.02.2015).

Host institution: Fondation faune-flore @ Centre de recherche scientifique, Musée national d’histoire naturelle.

Contact

Lucile Decanter
Musée national d’histoire naturelle
Centre de recherche scientifique
Laboratoire/Section Biologie des populations
24, rue Münster
L-2160 Luxembourg
phone: (+352)46 22 40 224
fax: (+352) 46 38 48

Publications and not published works

  • Decanter L. 2010. Etude de l’effet de croisement au sein et entre populations de Saxifraga rosacea (Saxifragaceae). 1rst year Master thesis, University of Metz, France.
  • Decanter L. 2011. Diversité et structure génétique de Saxifraga rosacea subsp. sponhemica (Saxifragaceae). Master thesis, University of Metz, France.

Talks and poster presentations